1. Field of the Invention
The present invention relates to an automatic contour-conforming support pallet and, more particularly, to a holding pallet for providing total and positive support for an object which is being subjected to a force capable of distorting or destroying it if unsupported.
2. Description of the Prior Art
There are numerous circumstances where an object is subjected to a force capable of distorting or destroying it if unsupported. While providing such support presents no particular problem when the object has a flat or regular surface, providing suitable support is often a serious problem where the supported surface of the object is irregular and/or is subject to change.
A typical example of the latter situation is found in the testing of electronic assemblies, such as printed circuit boards having discrete components mounted on one side thereof and a plurality of electrical contact points on the other side thereof. A widely accepted and proven method for testing such electronic assemblies is to connect them to an automatic circuit analyzer which is capable of performing several thousand tests per minute. Various ways are used to connect the assembly to the circuit analyzer. One circuit analyzer includes a plurality of spring-loaded probes supported in parallel, spaced-apart relationship and connected to the analyzer circuitry. The probes are brought into contact with the contact points of the circuit board, thus establishing a conductive path between the analyzer circuitry and the components mounted on the circuit board.
Such probes, by virtue of being spring loaded, exert a force on the circuit board during the testing procedure. While the force exerted by each probe is only on the order of a few ounces, it is multiplied by the number of probes, resulting in a total force of many pounds over the surface area of the circuit board. If the board is supported only around the edges thereof, the center of the board will be deflected relative to such edges. This can crack the discrete components mounted on the board and/or the conductive strips on the board, and can damage or crack the connecting adhesive between the multiple layers of a multi-layer board. Thus, under such circumstances, it is absolutely essential to support the entire surface of the board.
One common approach to the solution of this problem is simply to support the component side of the circuit board on a flat surface, which surface contacts only some of the circuit components. As a result, less than all of the components support all of the weight of the testing force. While such a procedure has often been acceptable in the past, when using rugged components having the capability of withstanding the total applied force, such a procedure is often unacceptable with new, more sensitive components, such as crystals and the like, which cannot tolerate such forces.
One common technique for distributing the force over substantially the entire surface of the board is to use a support surface which has been molded or formed to conform to the contour of the supported surface of the object under test. While such technique is obviously effective for many identical products, it is not necessarily effective for all identical products since normal manufacturing tolerances simply prevent all products from being identical and such molded supports cannot adjust themselves for variations among the same product. Furthermore, a different support must be made for every different product and this is time-consuming and costly.